Review of Data Gap Analysis for Extended Storage and Transportation

Review of Data Gap Analysis for
Extended Storage and Transportation
of Used Fuel
Hatice Akkurt1 and John Kessler2
1Senior Project Manager
2Program Manager
Used Fuel High Level Waste (UFHLW) Management Program
NRC DSFM REG CON
NRC HQ, Rockville MD, November 19, 2014
Data Gap Analysis Reports
• Nuclear Waste Technical Review Board (NWTRB) Gap Analysis
• Evaluation of the Technical Basis for Extended Dry Storage and
Transportation of Nuclear Fuel, published December 2010
•
Available from http://www.nwtrb.gov/reports/eds-final.pdf
• US Department of Energy (DOE) Gap Analysis Reports
• Gap Analysis to Support Extended Storage of Used Nuclear Fuel,
Rev 0, FCRD-USED-2011-000136, published January 2012
•
Available from http://www.osti.gov/scitech/biblio/1133836
• US Nuclear Regulatory Commission (NRC) Gap Analysis
• Materials Aging Issues and Aging Management for Extended Storage
and Transportation of Spent Nuclear Fuel, NUREG/CR-7116,
published November 2011
•
Available from http://pbadupws.nrc.gov/docs/ML1132/ML11321A182.pdf
© 2014 Electric Power Research Institute, Inc. All rights reserved.
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Data Gap Analysis Reports
• Electric Power Research Institute (EPRI) Gap Analysis
• Extended Storage Collaboration Program (ESCP) Progress Report and
Review of Gap Analysis, EPRI-1022914, published August 2011
• Available from
http://my.epri.com/portal/server.pt?Abstract_id=000000000001022914
• EPRI International Subcommittee Data Gap Analysis Report
• International Perspectives on technical data Gaps Associated with
Extended Storage and Transportation of Used Nuclear Fuel, EPRI1026481, published November 2012
• Included contributions from seven countries
• Germany, Hungary, Japan, Korea, Spain, UK, US
•
Available from
http://www.epri.com/abstracts/Pages/ProductAbstract.aspx?ProductId=00
0000000001026481
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DOE Prioritization Criteria
1.Whether existing data are sufficient to evaluate the
degradation mechanism and its impact on an “important to
safety” (ITS) systems, structures, and components (SSCs)
2.The likelihood of occurrence of the degradation mechanism
during extended storage
3.Ease of remediation of the degraded SSC such that it
continues to provide it safety function
4.The significance of the potential consequences that may
result from the degradation mechanism.
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EPRI Prioritization Criteria
• The importance to maintaining the safety functions with particular
emphasis on the confinement safety function.
– Primary confinement barrier: stainless steel canister or bolted lid
– Secondary confinement barrier: used fuel cladding
• The amount of relevant R&D that has already been completed.
– If there is significant amount of data, then priority is “low”
• Whether the data gap is the subject of significant, on-going research.
– If much relevant R&D is underway, then priority is “low”
• The ability to fairly easily detect, inspect, or mitigate degradation of the
safety function(s) affected by the long-term process being considered.
– If detection, inspection, or mitigation is “easy”, then priority is “low”
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DOE/EPRI Prioritization Similarities and
Differences
• Similarities
–
–
–
–
Maintain safety functions
Whether degradation mechanism will occur and its significance
Ability to detect, inspect, and mitigate
Regulatory requirements
• Differences
– Safety functions
• DOE: all safety functions of equal importance;
• EPRI: confinement is the primary safety function; retrievability may
be optional for transportation after very long-term storage
– Impacts on future waste management strategies:
• DOE: consider this (e.g., ease of disposal)
• EPRI: no disposal criteria, so no way to consider this
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Comparison of Priorities for Main Areas
1. Condition of used fuel at the time of transport
– Main issues: hydride reorientation; creep
2. Condition of the welded canisters
– Main issues: canister general corrosion and stress corrosion cracking
3. Structural and shielding properties of concrete
– Main issues: behavior of concrete under elevated temperatures and
radiation fields
• NWTRB: No prioritization, identified as gaps
DOE
NRC
EPRI
Fuel/Clad
High
Medium
Medium
Internal/Canister
High
High
High
Overpack/ISFSI
Medium
M/L
Low
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Extended Storage Technical Gaps
Structure,
System,
Component
Degradation
Mechanism
Germany Hungary
Annealing
Pellet
Assembly
hardware
Basket
ROK
Spain
UK
USA
High
Medium
Medium
High
Medium
High
High
High
High
High
Medium
High
Medium
High
High
Medium
H2
embrittlement
H2 hydride
cracking
Cladding
Japan
Oxidation
Medium
Medium
Medium
High
High
Medium
Creep
Medium
Medium
Medium
Medium
High
Medium
Low
Medium
High Burn-up
Fuel
MOX Fuel
Cracking,
bonding
Medium
High
Corrosion
Corrosion,
irradiation
© 2014 Electric Power Research Institute, Inc. All rights reserved.
Medium
Medium
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High
Medium
Extended Storage Technical Gaps
Structure,
System,
Component
Neutron
poisons/
shielding
Welded
canister
Moisture
absorber
Bolted cask
Metal gasket
Overpack /
Cask
Degradation
Mechanism
Thermal aging
Creep
Embrittlement
Corrosion
Atmospheric
corrosion
Aqueous
corrosion
Irradiation,
thermal
Fatigue of
seals, bolts
Atmospheric
corrosion
Aqueous
corrosion
Creep
Freeze-thaw
Corrosion
© 2014 Electric Power Research Institute, Inc. All rights reserved.
Germany Hungary
Japan
Medium
High
High
High
High
ROK
Spain
Medium
Medium
Medium
Medium
Medium
High
Low
UK
USA
Medium
Medium
Medium
Medium
High
High
High
High
Medium
High
High
High
Medium
Medium
High
High
High
Low
Low
Medium
Medium
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Medium
Low
High
Medium
Medium
Potential Approaches for Obtaining Data
Destructive Examination
Fuel
PIE
• Metallography
• Hydride and thermal
embrittlement
• Corrosion
Internals/
• Marine environment
SSC on canister
• Neutron poison mat’l
examination
Canister
Overpack/
Non-destructive
Examination/
Analysis
• Limit excursion
High burnup fuel
temperatures/time
• Hydride reorientation
during dry loadiing
• Hydride embrittlement
• Thermal embrittlement
• Corrosion
• Creep
• Fuel modeling & analysis
• Eddy current inspection • Stress corrosion cracking • Mitigative measures
for SCC in marine
on canister welds
environments
• Salt concentration
measurement on
canister surface
ISFSI
Transportation • Measure internal Kinetic Energy • Model and analyze fuel
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Aging Management
Plan
Physical Measurements
• Creep
• Visual inspections
(KE) from a 1-meter drop
test
Accelerated Aging
Applications
response to a 1-meter
drop test (incorporate
findings from
corrosion, hydride
degradation and KE
inputs to analysis)
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• SCC/Corrosion of seals
and bolts
• Concrete inspection
and repair
• Closure
lid/bolts/seals
inspection and repair
Ongoing Work to Fill Gaps: High Burnup Fuel
• Additional laboratory property testing: ANL, KAERI, CEA,
Studsvik, INL, PSI
• Confirmatory testing (included thermal benchmarking data)
– US: full-scale test being planned (2017)
– Japan: part-scale test (two HBU assemblies)
• First 43 GWd/MTU assembly (late 2014)
• Second ~55 GWd/MTU assembly (~2024)
– Korea: six HBU rods
• Normal conditions of transport
– SNL shaker table tests
– ORNL fatigue tests
– Later: over-the-road/rail test
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Ongoing Work to Fill Gaps: Welded, Austenitic Stainless Steel
Canisters:
Chloride-Induced Stress-Corrosion Cracking (CISCC)
• Failure Modes and Effects (EPRI)
• Susceptibility assessments (EPRI, SNL, NRC)
• Weld residual stress (SNL, MIT)
• Minimum chloride surface concentration
– Completed: Japan (CRIEPI), SwRI, others
– More needed
• Correlate atmospheric chloride concentration to amount of
canister deposition: Japan (CRIEPI)
– More needed
• Initial field inspections (EPRI/DOE)
• Improved NDE and delivery systems: underway by EPRI, DOE,
universities, cask vendors
• Mitigation: not yet started
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Work to Fill Gaps: Bolted Metal Lid Cask
Systems
• O-ring degradation: Germany (BAM), Japan (CRIEPI)
• Bolt degradation: Germany (BAM)
• Neutron shielding degradation: France (AREVA), Germany
(BAM)
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Ongoing Work to Fill Gaps: Concrete
Degradation
• Concrete and rebar degradation: EPRI, Slovenia,
Argentina, DOE, many others not related to long-term used
fuel storage
• Partial inspections: vendors
• Only minor additional work is thought to be needed
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Update of DOE Gap Analysis Report
• An effort to review work performed by UFDC over the past four
years
– Includes review of work done by others both in the US and international
organizations
• Based on what has been learned, timing of data needs, and what
still needs to be done, the gap prioritization is revisited
– No new gaps are identified
– Some of the work is deferred or priority is changed. Few examples:
• Bolted cask: Since there is significant activity by international organizations
(France, Germany, Japan)
• Burnup credit: No longer a near-term need because of the issuance of ISG8 Rev 3 addresses the more significant PWR UNF Burnup Credit gap and
because there are no near-term plans to transport canisters/casks for which
burnup credit is required.
• Expected to be published before the end of the year
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Update of International Data Gap Report
• Previous contributed countries (Germany, Hungary, Japan, Korea,
Spain, UK, US) will provide update on sections including
– current status of used fuel storage,
– current regulatory framework, and
– data gap status.
• New countries will be included in the updated report
– France
– Russia
– Argentine
– Switzerland*
– Sweden*
– Taiwan*
*Considering to participate but not fully confirmed yet
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Summary
• Based on the draft Updated Review of DOE Gap report
and EPRI ESCP International Data Gap analysis report,
in preparation:
– No new gaps have been identified
– None of the gaps have been fully closed, though progress
has been made in many areas. Focus is on:
– Cladding hydriding
– SCC of canisters/welds
– The status of gaps and ongoing work related to fuel/internals, CISCC
and NDE for improved inspection, and international status will be
discussed in detail during ESCP meeting
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Summary
• There is good information exchange and collaboration
between different organizations
– Extended Storage Collaboration program
– Individual bi-lateral agreements
• Updated DOE Gap report will be published before the end
of 2014
• Updated EPRI ESCP International Subcommittee Data
Gap report will be published in 2015
© 2014 Electric Power Research Institute, Inc. All rights reserved.
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